This invention relates to a mechanical pencil having a mouth piece which is extendable and retractable in and out of the main body of the pencil, and a lead enclosing tip sleeve which is similarly extendable and retractable in and out of the front end of the mouth piece. The lead can be extended out of the tip sleeve to a desired length in a step wise manner by the repeated, partial depression of a rear cap, and the tip sleeve automatically yields under writing pressure to keep the writing lead exposed and obviate the need for frequently extending fresh lead.
It is hazardous for a person to carry a mechanical pencil with its mouth piece and tip sleeve extended, since physical injury due to the sharp tip may result and/or the persons clothes may be torn. In order to overcome this hazard U.S. Pat. No. 3,724,960 teaches a mechanical pencil in which the tip sleeve is extended from the main body for writing, but can be retracted within the body when carried by a person. Further, U.S. Pat. No. 3,537,799 teaches a mechanical pencil in which the tip sleeve can be extended and retracted in and out of the end portion of the mouth piece as desired. The tip sleeve of this patent is so designed that the lead can be extended out to a relatively long length, and the tip sleeve automatically moves inwardly in response to writing pressure to keep the end of the lead exposed. Writing can be continued until the tip sleeve is entirely pushed back into the body, whereby it is unnecessary to frequently extend fresh lead during writing.
However, no mechanical pencil combining the two features described above, that is, a mechanical pencil in which the mouth piece and the tip sleeve can be retracted within the body, and in which the tip sleeve can also be extended and retracted in and out of the mouth piece as desired, has yet been proposed.